The invention relates to a spring and an apparatus for its use with an exhaust system.
An exhaust system can be very susceptible to vibration from an engine, such as in an ultralight aircraft. If the exhaust system is constructed as a unitary welded structure, the walls of the exhaust system are very susceptible to stress cracking. This problem is solved by constructing the exhaust system from at least two, and most preferably three, sections that are flexibly joined to one another. The sections are connected with ball joints that are held together with springs, thereby allowing relative movement between the joined sections. Adjoining sections have metal loops welded thereto for securely receiving opposing hooks of each spring.
In an ultralight aircraft having its engine and exhaust system uncovered and exposed, breakage of a spring or loop can result in damage to vital aircraft components. In an aircraft (i.e. powered parachute) with a pusher propeller positioned to the rear of the engine and exhaust system, a broken spring, or a broken loop and the spring, can fly into and damage the propeller. Aside from the cost of replacing the damaged propeller, a portion of a propeller blade could be lost in flight and result in severe vibration, which can then lead to damage to the remainder of the propeller as well as the engine or gear box. The pilot may then be forced to land the aircraft without the assistance of the engine driven propeller.